From the ARRL Website:
SKYWARN Recognition Day is Saturday, December 2
A heads up: SKYWARN™ Recognition Day (SRD) will take place this year on Saturday, December 2 from 0000 until 2400 UTC (starts on the evening of Friday, December 1, in US time zones). During the SKYWARN Special Event, ham radio operators will set up stations at National Weather Service (NWS) offices and contact other radio amateurs around the world.
Participating Amateur Radio stations will exchange a brief description of their current weather with as many NWS-based stations as possible on 80, 40, 20, 15, 10, 6, and 2 meters plus 70 centimeters. Contacts via repeaters are permitted.
SRD was developed jointly in 1999 by the NWS and ARRL to celebrate the contributions SKYWARN volunteers make to the NWS mission — the protection of life and property. Amateur Radio operators, which comprise a large percentage of SKYWARN volunteers, also provide vital communication between the NWS and emergency managers, if normal communications become inoperative.